Process doc. &, trans./ev. type &, with different transaction

What causes this issue?

The function is not defined for the
<GL:transaction/event_type>transaction/event type</> of this document.
Example: you want to enter a goods issue with reference to a material
document but have entered a goods receipt document as reference.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Enter a different document or process the document with the function
that has been defined for it.
Do you want to <DS:TRAN.MB51>display</> the list of material documents
for the material? If so, you can select by transaction/event type.

Error message extract from SAP system. Copyright SAP SE.